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glibc/sysdeps/ieee754/ldbl-128ibm/s_nextafterl.c
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/* s_nextafterl.c -- long double version of s_nextafter.c. | |
* Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz. | |
*/ | |
/* | |
* ==================================================== | |
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | |
* | |
* Developed at SunPro, a Sun Microsystems, Inc. business. | |
* Permission to use, copy, modify, and distribute this | |
* software is freely granted, provided that this notice | |
* is preserved. | |
* ==================================================== | |
*/ | |
#if defined(LIBM_SCCS) && !defined(lint) | |
static char rcsid[] = "$NetBSD: $"; | |
#endif | |
/* IEEE functions | |
* nextafterl(x,y) | |
* return the next machine floating-point number of x in the | |
* direction toward y. | |
* Special cases: | |
*/ | |
#include <errno.h> | |
#include <float.h> | |
#include <math.h> | |
#include <math_private.h> | |
#include <math_ldbl_opt.h> | |
long double __nextafterl(long double x, long double y) | |
{ | |
int64_t hx, hy, ihx, ihy, lx; | |
double xhi, xlo, yhi; | |
ldbl_unpack (x, &xhi, &xlo); | |
EXTRACT_WORDS64 (hx, xhi); | |
EXTRACT_WORDS64 (lx, xlo); | |
yhi = ldbl_high (y); | |
EXTRACT_WORDS64 (hy, yhi); | |
ihx = hx&0x7fffffffffffffffLL; /* |hx| */ | |
ihy = hy&0x7fffffffffffffffLL; /* |hy| */ | |
if((ihx>0x7ff0000000000000LL) || /* x is nan */ | |
(ihy>0x7ff0000000000000LL)) /* y is nan */ | |
return x+y; /* signal the nan */ | |
if(x==y) | |
return y; /* x=y, return y */ | |
if(ihx == 0) { /* x == 0 */ | |
long double u; /* return +-minsubnormal */ | |
hy = (hy & 0x8000000000000000ULL) | 1; | |
INSERT_WORDS64 (yhi, hy); | |
x = yhi; | |
u = math_opt_barrier (x); | |
u = u * u; | |
math_force_eval (u); /* raise underflow flag */ | |
return x; | |
} | |
long double u; | |
if(x > y) { /* x > y, x -= ulp */ | |
/* This isn't the largest magnitude correctly rounded | |
long double as you can see from the lowest mantissa | |
bit being zero. It is however the largest magnitude | |
long double with a 106 bit mantissa, and nextafterl | |
is insane with variable precision. So to make | |
nextafterl sane we assume 106 bit precision. */ | |
if((hx==0xffefffffffffffffLL)&&(lx==0xfc8ffffffffffffeLL)) { | |
u = x+x; /* overflow, return -inf */ | |
math_force_eval (u); | |
__set_errno (ERANGE); | |
return y; | |
} | |
if (hx >= 0x7ff0000000000000LL) { | |
u = 0x1.fffffffffffff7ffffffffffff8p+1023L; | |
return u; | |
} | |
if(ihx <= 0x0360000000000000LL) { /* x <= LDBL_MIN */ | |
u = math_opt_barrier (x); | |
x -= LDBL_TRUE_MIN; | |
if (ihx < 0x0360000000000000LL | |
|| (hx > 0 && lx <= 0) | |
|| (hx < 0 && lx > 1)) { | |
u = u * u; | |
math_force_eval (u); /* raise underflow flag */ | |
__set_errno (ERANGE); | |
} | |
return x; | |
} | |
/* If the high double is an exact power of two and the low | |
double is the opposite sign, then 1ulp is one less than | |
what we might determine from the high double. Similarly | |
if X is an exact power of two, and positive, because | |
making it a little smaller will result in the exponent | |
decreasing by one and normalisation of the mantissa. */ | |
if ((hx & 0x000fffffffffffffLL) == 0 | |
&& ((lx != 0 && (hx ^ lx) < 0) | |
|| (lx == 0 && hx >= 0))) | |
ihx -= 1LL << 52; | |
if (ihx < (106LL << 52)) { /* ulp will denormal */ | |
INSERT_WORDS64 (yhi, ihx & (0x7ffLL<<52)); | |
u = yhi * 0x1p-105; | |
} else { | |
INSERT_WORDS64 (yhi, (ihx & (0x7ffLL<<52))-(105LL<<52)); | |
u = yhi; | |
} | |
return x - u; | |
} else { /* x < y, x += ulp */ | |
if((hx==0x7fefffffffffffffLL)&&(lx==0x7c8ffffffffffffeLL)) { | |
u = x+x; /* overflow, return +inf */ | |
math_force_eval (u); | |
__set_errno (ERANGE); | |
return y; | |
} | |
if ((uint64_t) hx >= 0xfff0000000000000ULL) { | |
u = -0x1.fffffffffffff7ffffffffffff8p+1023L; | |
return u; | |
} | |
if(ihx <= 0x0360000000000000LL) { /* x <= LDBL_MIN */ | |
u = math_opt_barrier (x); | |
x += LDBL_TRUE_MIN; | |
if (ihx < 0x0360000000000000LL | |
|| (hx > 0 && lx < 0 && lx != 0x8000000000000001LL) | |
|| (hx < 0 && lx >= 0)) { | |
u = u * u; | |
math_force_eval (u); /* raise underflow flag */ | |
__set_errno (ERANGE); | |
} | |
if (x == 0.0L) /* handle negative LDBL_TRUE_MIN case */ | |
x = -0.0L; | |
return x; | |
} | |
/* If the high double is an exact power of two and the low | |
double is the opposite sign, then 1ulp is one less than | |
what we might determine from the high double. Similarly | |
if X is an exact power of two, and negative, because | |
making it a little larger will result in the exponent | |
decreasing by one and normalisation of the mantissa. */ | |
if ((hx & 0x000fffffffffffffLL) == 0 | |
&& ((lx != 0 && (hx ^ lx) < 0) | |
|| (lx == 0 && hx < 0))) | |
ihx -= 1LL << 52; | |
if (ihx < (106LL << 52)) { /* ulp will denormal */ | |
INSERT_WORDS64 (yhi, ihx & (0x7ffLL<<52)); | |
u = yhi * 0x1p-105; | |
} else { | |
INSERT_WORDS64 (yhi, (ihx & (0x7ffLL<<52))-(105LL<<52)); | |
u = yhi; | |
} | |
return x + u; | |
} | |
} | |
strong_alias (__nextafterl, __nexttowardl) | |
long_double_symbol (libm, __nextafterl, nextafterl); | |
long_double_symbol (libm, __nexttowardl, nexttowardl); |